LITERATURE REVIEW: Repetitive Negative Thought and Anhedonia: A Systematic Review; EMPIRICAL PAPER: Repetitive Negative Thought and Reward Sensitivity
Thesis or dissertation
University of Exeter
Literature Review: Anhedonia, the loss of interest or pleasure in usually pleasurable activities, is a core symptom of depression and is associated with a reduction in positive affect (PA). Repetitive negative thought (RNT) is implicated in the development and maintenance of psychiatric disorders. It has been hypothesised that RNT causally contributes to anhedonia. The aim of this review was to explore this relationship to answer two questions: Is there a relationship between RNT and anhedonia? Does RNT causally contribute to anhedonia? Review inclusion criteria were: studies using standardised measures to report a relationship between RNT and anhedonia or reduced PA. Results suggest that cross-sectional and longitudinal studies identify a relationship between RNT and anhedonia. Preliminary evidence from experimental studies shows that RNT causally contributes to anhedonia. Limitations within the field are that anhedonia is rarely measured directly or behaviourally. Future research is warranted to explore the relationship between RNT and anhedonia with a particular focus on direct and behavioural measures of anhedonia. Empirical Paper: It is hypothesised that repetitive negative thought (RNT) causally contributes to anhedonia. There is cross-sectional and longitudinal evidence of this relationship, but it has not previously been investigated directly using experimental methods. In the present study, student participants were randomly assigned to an unresolved goal (RNT) manipulation (n = 43) or resolved goal (control) manipulation (n =41) prior to completing a reward sensitivity task. This task has been reliably found to train a response bias towards the stimuli that is differentially positively reinforced, with both depression and self-reported anhedonia associated with a reduced response bias. The unresolved goal versus resolved goal manipulation was effective, with the unresolved condition producing significantly higher levels of RNT during the reward sensitivity task relative to the resolved condition. Inconsistent with study predictions, there was no significant difference between the conditions on response bias, although there were trend findings, which tentatively suggest that RNT may influence anhedonia. Potential accounts for the null findings and future research are discussed.